Plastic bonded explosives rocket warhead



P 1951 w. E. LAND 2,998,772

PLASTIC BONDED EXPLOSIVES ROCKET WARHEAD Filed Sept. 2. 1955 INVENTOR.WILLIAM E. LAND flaw ATTORNE YS United States Patent 2,998,772 PLASTICBONDED EXPLOSIVES ROCKET WARHEAD William E. Land, 921 19th St. NW.,Washington, D.C. Filed Sept. 2, 1955, Ser. No. 532,379 Claims. (Cl.102-56) (Granted under Tifle 35, US. Code (1952), sec. 266) Theinvention described herein-may be manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

This invention relates to improvements in warheads, and morespecifically to the provision of minor caliber rocket warheads in whichthe permissible load of high explosive is of relatively much greaterweight than hitherto possible.

It has been common, in the past, to form warheads by filling heavy steelwarhead cases with explosives (usually by cast-loading techniques), thecases remaining integral parts of the missiles of which they form apart. Such warhead cases, in the example of minor caliber rocketwarheads, often weigh between two and three times more than theexplosive charges carried therein. For example, in the conventionalprior art constructions the steel warhead case of a 2.00-inch rocketweighs more than twice the weight of the explosive it carries and in a2.75-inch rocket the warhead case weighs more than three times theweight of explosive.

Distinct advantages in performance relative to blast damage potentialmay be realized by decreasing the amount of steel as much as possiblethereby making it possible to carry greater weights of explosiveswithout impairing performance of the rocket vehicle. The ultimateadvantage in this direction, of course, would be attainable in theprovision of means entirely eliminating the necessity for a metalliccasing or other heavy metallic parts.

It is, therefore, an object of this invention to provide warheadstructures in which the permissible pay load of high explosive materialsis a higher percentage of the warhead weight than was previouslypossible.

It is another object of this invention to provide such new structuralshapes and forms of explosive materials as to obviate the need formetallic casings therefor when used as warheads.

It is still another object of this invention to provide more simplymanufactured and more economical warhead structures by obviating theneed for providing and machining the metal case commonly used in theprior art.

A still further object of this invention is to provide a warhead inwhich plastic bonded explosive is of such form as to provide means forsimple direct connection to the missile body and to a nose fuze, withoutrecourse to metal parts for effecting such connections.

Still another object of this invention is the provision of a warheadformed of plastic bonded explosives and of such strength that strongmetallic casings or supports are not essential to the structure althoughthin protective skin members may be used if desired.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreferences to the following detailed description when considered inconnection with the accompanying drawings wherein:

FIG. 1 is a vertical sectional view of a warhead constructed inaccordance with the invention; and

FIGS. 2 and 3 aresimilar sectional views of two other modifiedstructures illustrating the principles of the invention and possiblevariations thereof.

As will become obvious from the ensuing detailed de- Patented Sept. 5,1961 scription, the instant invention is concerned primarily withwarhead structural features which make possible the exclusion of the useof metallic parts to a very large degree. In the broadest sense,therefore, the explosive materials used need only be capable of beingcast or molded into shape in order to practice the invention.

One type of such material has become known as plastic bonded explosive.Plastic bonded explosives (PBX) as used in this disclosure, is a genericterm. It could comprise any solid explosive combined with any plasticbinder. To mention a few examples, PBX could be a combination of RDX andstyrene-modified polyester; PETN and epon-type plastic binder, HMX andacrylate-type plastic binder, etc. Thus, materials in this category maybe described, in general, as each comprising particles of a particularexplosive compound or mixture of explosive compounds bonded together byparticular plastics and in which the resulting compositions, whenpressed into struc tural shapes in molds, have considerable rigidity andstrength. A typical group of such materials are formed by mixtures ofexplosive material such as RDX, which is cyclo trimethylene trinatraminewith conventional plastics, as for example, polystyrene plasticized withdioctylphthalate. In the formation of plastic bonded explosives fromsuch materials, the resulting compositions contain explosive material inthe order of percent by weight and plastic materials (includingplasticizer) in the order of 10 percent by weight. Typical examples areas follows:

90% RDX 9% polystyrene 1% dioctylphthalate 70% RDX 20% atomized aluminum8.5% polystyrene 1.5% dioctylphthalate Such compositions may be formedby any of the well known prior art methods. As an example of one method,a lacquer may be formed by mixing the desired amount of plastic(polystyrene) and plasticizer (dioctylphthalate) in a suitable solvent(such as toluene) to form a viscous lacquer. The lacquer is placed in amixer and the required quantity of explosive is added. During mixing,the material in the mixer is treated by heat and vacuum to distill offthe solvent and the resulting composition is in the form of non-cohesivelumps of material. The material thus formed may be formed into shapes byknown molding techniques, as by pressing into a mold (preferably of thesplit type) having a cavity of the intended shape. The material ispressed at pressures exceeding 10,000 pounds per square inch and aftersuch pressing operation is extruded and is allowed to cure.

Attention is directed to the drawing, in all of the figures thereof, inwhich the reference numeral 12 represents a block of explosive materialin the form of a warhead. Warhead 12 may be formed by the casting ormolding of known explosive materials in known manners, specific examplesof some of the usable materials and the techniques of manufacture andmolding thereof being given hereinabove.

Referring now to FIG. 1, warhead 12 is provided with a frontal cavity 13with a molded thread course 14 into which a fuze (not shown in FIG. 1)can be screwed directly. It is also provided with an externally threadedboss 16 which is adapted to be screwed directly into a complementarycavity of a rocket motor 17. Thus, the molded block of explosivematerial, without metal parts of any kinds serves as a structuralconnecting piece with the fuze and the rocket motor connected directlythereto to complete a rocket assembly in which, as discussed above, thepermissible pay load of explosive material is much greater thanhithereto possible.

FIG. 2 illustrates an alternate mode of construction in which a lightmetal insert 18, having screw threads 14a thereon is fitted in a frontalcavity 13 which is itself not threaded. Such a construction does awaywith the difficulties involved in molding threads on the warhead body.The fuze 15 may then be screwed into the insert 18, as shown. The metalbase headclosure 19 is at tached to the aft end, as by cementing. Alight-metal, ogival, truncated cone 20 may, if desired, be attached tothe warhead body 12, by any means, as for example, by cementing, tofacilitate target penetration.

FIG. 3 is identical with FIG. 2 but illustrates a further variation ofthe principle of this invention in that it discloses a very light metalor plastic case 21 extending the full length of the explosive block andoverlapping the flange of the closure 19. This case 21 is extremely thinand of light material, as for example, a mere skin ,64 to thick ofaluminum or magnesium or a coating of tough, fire-resistant plasticmaterial. Such a skin protects the surface of block 12 from damage andadds only a small amount of inert weight and is not to be interpreted asa reversion to the heavy metallic warhead casings of the prior art sincethe light casing contemplated in this invention serve no particularfunction of structural support at the expense of explosive pay load asis true of the prior art casings.

It should be obvious from the foregoing that the instant inventionprovides new and useful improvements in warhead structures, resulting inincreasing the load of explosive material which may be carried by agiven missile, in simplifying the fabrication of warheads, and in thesavings in cost of warheads resulting from said simplification.

Obviously, many modifications and variations of this invention arepossible in the light of the above teachings. It is therefore to beunderstood that the invention is not intended to be limited to thespecific modifications herein illustrated and discussed, its scope beingdefined by the appended claims.

What is claimed is:

1. A warhead for high-speed missiles, said warhead comprising a unitaryblock of high-strength explosive material capable of withstanding flightand impact without appreciable deformation and of serving as the solestructural element connecting and supporting forward and aft elements ofa missile without reinforcement, said block having a base memberattached to the rearward end thereof, said base member having means foreffecting attachment to a missile body, said block having also a frontalcavity, a metal insert secured into said frontal cavity, said inserthaving means to effect connection with fuze means.

2. A warhead according to claim 1 having also a lightmetal, ogival,truncated, cone-shaped member, attached to the external surface of theforward end of the said block to facilitate penetration of a target,said coneshaped member being supported solely by said block and havingno structural connection with said forward and aft missile elements.

3. A warhead according to claim 1 having an external casing in the formof a thin skin of protective material extending substantially the fulllength of the block, but terminating slightly aft of the forward end ofsaid block whereby the block rather than the external casing serves toconnect the forward and aft missile elements and maintain them in properstructural alignment during flight and impact.

4. A warhead according to claim 3 in which said casing is oflight-weight metallic material.

5. A warhead according to claim 3 in which said casing vis of a toughfire-resistant plastic material.

References Cited in the file of this patent UNITED STATES PATENTS1,316,005 Vautln Sept. 16, 1919 2,500,117 Chandler Mar. 7, 19502,632,391 Kintzinger Mar. 24, 1953 2,671,401 Abramson Mar. 9, 19542,750,884 Gaines June 19, 1956 FOREIGN PATENTS 843,734 France Apr. 3,1939

